"I love my boyfriend."
It is a well known point that "with-Duo-only" you cannot learn everything. It is good for pattern learning, but not so good to stamp vocabulary in your memory. Not to mention grammar... The positive thing is that you must be searching by yourself, which is not bad. Reading all these comments is also good: I am not alone!!! LOL
In every Japanese class I was told to never use "愛をして" because it is too strong, because as foreigners it is a bit hard to understand Japanese way of thinking (like parents usually tell a child to work hard instead of telling them how much they love them and so on) and here we are... I can't recall how often they told us at university to please not use it. A Japanese teacher said it made her so uncomfortable when she heard students saying it... we should please stick to 好き or 大好き. But oh well...
Even with romantic love, they tend to use 好き or 大好き... 愛 is a very forceful/strong love, someone else said it's something you'd hear when someone's on a deathbed, or maybe in a story where they might never see someone again and it's incredibly strong... I learned in class that they confess their love by saying, in literal translation, "I like your things" to be indirect and not too forward about it. If even in confessing they don't tend to say 好き or 大好き then this feels beyond even that. Some teachers described it as "PASSIONATELY love" (capitalization to bring across the amount of force behind it)
Technically 愛し means love and 好き means like, while 大好 means like a lot. But in practice 大好 is used to mean love and 愛 is rarely used. A side note, when my Japanese boyfriend told me in English that he loved me, I asked him to say it in Japanese, wondering if he would use 好き or 大好き. When he used 愛し I knew it was really serious to him!