Is he really ready for commitment? I'm scared, need advice.

I have a wonderful 31 year old boyfriend. He's loving, thoughtful & affectionate. In short, he treats me and my dogs very well. We've just signed a 12 month lease, I'm moving in this week. He'll move in fulltime in Jan, when his current lease ends. We're planning to try & pregnant from April. He seems happy about this. Ahead of that, we're doing IVF (freeze all embryos) in 2 weeks as we were told by a specialist not to wait as a blood test and scan indicates low egg reserves (if we try naturally first, then need to do IVF in a year, it could be too late, also as we want 2 children). He's onboard and done semen samples, come to appointments and counselling and we'll share all costs. Here is what's worrying me a lot. Maybe 8 weeks ago, when I came to live in his flat for a while, I noticed when using his computer, he searches girls names. I know at least 2 are his exes from about 6-10 years ago, and 1 is a girl he saw casually for a while 6 years ago. He's dated, but was essentially single in the few years before we met. A couple of weeks ago, I spoke to him briefly about having noticed a search on one name (name: ex T). During our talk, I showed that it worried me & was confronting as we were starting our life together. I asked him if he had doubts or reservations. He said no, it was normal to reminisce from time to time, it was just nosy curiosity. He said she was actually a drama queen, he never wanted to feel the way he did about that relationship again, be in that situation. What he didn't realise was I'd noticed he'd searched several girls at least every few weeks. We'd been under a lot of external family, work and medical pressure, things had been hectic and in the last 3-4 weeks our sex life started to slow right down. I felt increased doubt in the face of the commitments we were about to make, so looked at his Facebook about 10 days ago. I knew he still had exes as FB friends, not real life, but he also follows them. But his search history was really worrying. He had looked up ex-T about every 10-14 days, the other ex about every 2-3 weeks, and other girls I probably don't know are exes. The searches seemed to happen since before 'us' but had increased in the last 3-4 months. Including a few times since we talked about it. Somehow in the last week, he's worked out I looked, so as of a week ago, deleted all his FB search history. It was more than 12 months history showing until this week. Suddenly it's all gone. This is in addition to his standard computer search history, which I think he's been deleting some of since we talked 3-4 weeks ago. I have twice told him since we talked that I'm not comfortable with him remaining FB friends with long ago exes, but he shrugs it off & seems annoyed. I saw on his laptop tonight he'd searched his other ex just 2 days ago & other girls in the last week. He's just removing his trail off FB so I can't see. I'm alarmed his actively follows & looks them up so often. It makes me hestitate to have a family with him. Why does he want to keep a connection with updates & access to their private photos? It feels like an intrusion on us & our future family that he needs to track them & their lives regularly. Their presence remains in his present if they're on his FB feed. But I'm more disturbed with the frequency of his searches for them. I understand looking back occasionally eg twice a year, but at least fortnightly?! Given he now hides this (I know looking was wrong, but I needed answers before we made a baby) I feel like he'd argue about cutting ties and unfriending them. Especially seeing he's ignored that it bothers me. It's eating away at me. How can we discuss & resolve this? Please help.